/*
 *                               POK header
 *
 * The following file is a part of the POK project. Any modification should
 * be made according to the POK licence. You CANNOT use this file or a part
 * of a file for your own project.
 *
 * For more information on the POK licence, please see our LICENCE FILE
 *
 * Please follow the coding guidelines described in doc/CODING_GUIDELINES
 *
 *                                      Copyright (c) 2007-2021 POK team
 */

/* e_coshf.c -- float version of e_cosh.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#ifdef POK_NEEDS_LIBMATH
#include "math_private.h"
#include <libm.h>

static const float huge = 1.0e30;
static const float one = 1.0, half = 0.5;

float __ieee754_coshf(float x) {
  float t, w;
  int32_t ix;

  GET_FLOAT_WORD(ix, x);
  ix &= 0x7fffffff;

  /* x is INF or NaN */
  if (ix >= 0x7f800000)
    return x * x;

  /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
  if (ix < 0x3eb17218) {
    t = expm1f(fabsf(x));
    w = one + t;
    if (ix < 0x24000000)
      return w; /* cosh(tiny) = 1 */
    return one + (t * t) / (w + w);
  }

  /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
  if (ix < 0x41b00000) {
    t = __ieee754_expf(fabsf(x));
    return half * t + half / t;
  }

  /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
  if (ix < 0x42b17180)
    return half * __ieee754_expf(fabsf(x));

  /* |x| in [log(maxdouble), overflowthresold] */
  if (ix <= 0x42b2d4fc) {
    w = __ieee754_expf(half * fabsf(x));
    t = half * w;
    return t * w;
  }

  /* |x| > overflowthresold, cosh(x) overflow */
  return huge * huge;
}
#endif
